The present invention relates to a porous glass structure prepared by the sol-gel process. In particular, the invention relates to a porous glass structure which has an active biological material entrapped therein.
Enzymes are commonly used as reactants in manufacturing, catalytic and analytic processes. Encapsulated or entrapped enzymes are used with increasing frequency as micro-catalysts and analytic devices of very high sensitivity. For example, enzymes have been enclosed in membrane systems and used as high-sensitivity monitoring devices.
Such membrane systems, however, are cumbersome and difficult to miniaturize. The enzymatic reactions must be monitored by complex electronic means. Results from the systems are frequently unreliable and nonreproducible.
It would be highly advantageous to encapsulate enzymes in a porous, transparent glass structure, such as, such structures prepared by the sol-gel process. Such an encapsulation would be significantly easier to miniaturize and would be far less cumbersome and far more reliable than membrane encapsulation systems. Furthermore, enzyme encapsulation within a transparent glass structure would allow for the monitoring of many enzymatic reactions by using simple, photometric monitoring systems.
Unfortunately, a high activity enzyme encapsulation system using a porous, transparent glass structure has not as yet been demonstrated. Braun, et al., described in "Biochemically Active Sol-Gel Glasses: The Trapping Of Enzymes,"Materials Letters, Vol. 10, No. 1, Sept. 2, 1990, pp. 1-5, the encapsulation of an enzyme in a sol-gel glass. The reported activities of the enzyme encapsulated by Braun, et al., was only about 30%, it was not reported whether or not the glass was transparent and the Braun procedure did not result in a monolith.
Accordingly, there is a need for a porous, transparent glass structure which encapsulates an enzyme in such a way that the natural activity of the enzyme is not impaired.